This application claims the priority of German Patent Document No. 199 59 562.3, filed in Germany, Dec. 10, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a sweeping machine with two driven circular brooms, which can be rotated in opposite directions with respect to each other and sweep over a sweeping plate provided with an elastic sweeping lip. In the operational state of the sweeping machine the sweeping lip is positioned at least partially flush with the ground.
Such a sweeping machine is known from the German Patent Document DE 41 01 888 C2 (corresponding to U.S. Pat. No. 5,231,724). The prior art sweeping machine exhibits in a front area of a sweeping machine housing two laterally arranged circular brooms that can be rotated toward the inside in opposite directions to each other. The two circular brooms are driven by one roller each. Each roller stands up on a floor and is positioned inside a bristle ring of each circular broom. The circular brooms"" axes of rotation are sloped in such a manner relative to the sweeping machine housing that the bristles of the circular brooms sweep essentially over the front area of the ground. The circular brooms sweep the sweepings onto a sweeping lip, which is arranged between the circular brooms and whose front is mounted on a sweeping plate. The sweeping plate is positioned in front of a receptacle for the sweepings. The circular brooms sweep the sweepings over the sweeping lip onto the sweeping plate, where the sweepings are scraped off and thrown into the receptacle, located behind the sweeping plate, by means of the rotational movement of the circular brooms.
The sweeping lip is made of an elastic material and its ground-sided contact area is positioned essentially flush with the ground relative to the ground to be swept. Should the elastic is sweeping lip hit an impediment during a corresponding pushing movement of the sweeping machine, it can get caught on this impediment and be damaged.
An object of the invention is to provide a sweeping machine and a sweeping lip of the class described in the introductory part above that enables a flawless sweeping operation even under uneven ground conditions.
This problem is solved by preferred embodiments of the invention in that, starting from its ground-sided contact area, the sweeping lip is designed so as to be increasingly flexible in the direction of an upper-sided sweeping area so that, when the sweeping lip encounters an impediment, the front edge of the sweeping lip performs an automatic elastic avoidance movement in the upward direction. With the inventive solution the sweeping lip will perform with its front edge an avoidance movement in the upward direction upon encountering an impediment, whereby the sweeping lip can slide over the impediment. In the state of the art, however, an impediment could result in the sweeping lip overturning in the downward direction and thus result in damage or result in the sweeping lip detaching itself. During the analysis of these cases of damage, the solution of the invention arrived at the recognition that an automatic avoidance movement of the front edge of the sweeping lip in the upward direction upon encountering an impediment could avoid such problems and damage. Thus, the inventive solution combines increased rigidity of the sweeping lip in the ground-sided contact area with reduced rigidity in the upper-sided sweeping area. Thus, when the sweeping lip is subjected to compressive strain, the front edge of the sweeping lip automatically evades the impediment in the direction of the weak side and thus moves upwardly. In this manner an essentially improved sweeping operation is achieved that can be carried out without difficulty especially under uneven ground conditions. Such uneven ground conditions are found in particular on walkways with individual, protruding paving stones, in the area of flat curbstone corners, in the area of sewer covers and sewer holes and the like.
In the design of certain preferred embodiments of the invention the sweeping lip is molded as one piece to the sweeping plate. In contrast to the alternative solution that is also within the scope of the invention and in which the sweeping lip is fastened as a separate component to the sweeping plate in the front, a simplified manufacturability is achieved with this design.
In certain preferred embodiments of the invention, the upper-sided sweeping area of the sweeping lip exhibits material weakening structures. Such material weakening structures are preferably of a geometric nature, in that there are corresponding profilings in the area of the upper side of the sweeping lip.
In certain preferred embodiments of the invention, at least one reinforcement insert is integrated into the ground-sided contact area. Thus, the ground-sided contact area is reinforced relative to the upper-sided sweeping area so that the result is a desired varying rigidity between the top and bottom side, which can lead to an automatic elastic avoidance movement.
In certain preferred embodiments of the invention at least one notch, which runs at right angles to the normal direction of travel of the sweeping machine, is provided in the upper-sided sweeping area as the material weakening structure. This measure facilitates the vertical adjustment of the front edge of the sweeping lip in the upward direction upon encountering an impediment.
In certain preferred embodiments of the invention, the upper-sided sweeping area is formed by a softer elastomer material than the ground-sided contact area. During production of the sweeping lip this design is accounted for in that a nonhomogeneous elastomer mixture with correspondingly different properties is inserted between the bottom contact area and the upper sweeping area for the production of the sweeping lip. In so doing, both the ground-sided contact area and the upper-sided sweeping area exhibit a specific height, i.e. thickness, that can pass over flowingly into the other.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.